This Small Business Innovation Research (SBIR) Phase II project will use in vitro three-dimensional (3D) cell culturing enabled by the magnetic levitation method (MLM) as an improved tool for toxicity testing. This work will probe the effects of common agents on the lung, liver and kidney, three organs that play a central role in drug metabolism and are predisposed to toxic injury. 2D cell culture, commonly utilized for testing the cytotoxic effects of drugs, displays limited accuracy in predicting toxicity in vivo due to fundamental differences in the cellular microenvironment. While better representations of the 3D architecture of in vivo tissue are provided by animal models, they fail to accurately reflect whether or not drugs will cause cellular damage in humans as a result of biological differences between species. Our preliminary data shows that magnetic levitation maintains cells in culture in an arrangement that allows the cells to develop and communicate in a manner that is much closer to the in vivo environment than other in vitro systems. The broader impacts of this research are to improve assessment of drug toxicity and chemical hazards, reduce the use of animals, and advance the fields of in vitro toxicology testing and drug discovery. Commercial potential includes expansion of the device into high-throughput screening, generation of a prototype of a gas delivery system with capabilities to perform live cell microscopy, and development of a label-free viability assay for drug discovery and toxicity testing.